can't say I'm a fan of this piece really. Variable size outline? Hm... 5 colours and your way to lighting makes for almost pillow shading in places. Even if it's not strictly realistic, I suggest you accentuate volumes in less rounded ways. He looks like he's made of cylinders, which he might be, but that's not very interesting to look at, is it?
Also, crotch stretch marks on skin? Probably not the best idea ever unless you plan to put him in a pair of blue jeans, which might actually be fun and help the 'character' issue you're talking about.
Right now you might struggle a lot but you have 5 colours and there's only so much you can do with that. You can do the fur texture sure, but for accessories you'll have to eventually add more colors.